1. Field of the Invention
The present invention generally relates to a computer output microfilmer (COM) system and, more particularly, to a multi-form slide selection apparatus for the COM system which allows specific one of multiple form slides to be selected and then its form to be projected to a microfilm or like record medium, together with computer output video patterns which appear on such a display as a cathode ray tube (CRT).
2. Description of the Prior Art
In one prior art COM system, desired data output from a data processing system is caused to appear on a CRT or like display while, at the same time, one of multiple form slides carrying a form associated with the displayed information is selected. The displayed information and the form on the selected slide are picked up by a common imaging system to be recorded on one frame of a microfilm in a superposed manner. For example, the information displayed on the CRT may be the balances of personal bank accounts in which case a selected form is often made up of rules.
In another prior art COM system, an image pattern on a selected form slide is scanned with a laser beam to be transformed into a time serial video signal. Meanwhile, information output from a data processing system is coverted into a time serial video signal with or without the intermediary of a magnetic tape or the like. These time serial video signals are combined together to be recorded on a microfilm.
The prerequisite in the two systems described is that a form matching to a specific format of data to be recorded on the microfilm be selected out of a number of form slides in response to the content and property of computer output data.
To meet this requirement, COM systems now in use are furnished with a device for selecting a desired form, i.e., a multi-form slide selection device. One known approach to such a device is a form slide stocker which stores, for example, ten form slides stacked one upon another and is movable up and down with respect to a predetermined position. A selected form is discharged from the stocker to automatically intersect a predetermined optical axis of optics in the predetermined position. Another known approach is a straight form slide holder which has, for example, ten form slides arranged linearly thereon and is movable to locate a desired form in register with an optical axis of optics.
The problem commonly encountered with the approaches discussed above is that the time period consumed for the selection of a desired form is disproportionately long compared to the processing time of the computer system connected to the form selector. The slide selector with the stocker, for example, requires four seconds for the replacement of immediately neighboring forms and eight seconds for that of the top and bottom forms in the stack. Throughout the replacement period, recording data into the microfilm should be interrupted at the sacrifice of efficiency of the whole COM system. The slide selector with the holder is little better than the one with the stocker, consuming one second for the replacement of neighboring forms and 10 seconds for that of forms at opposite ends.
Another important consideration in the COM system is the positional accuracy which is required for recording a form on a form slide on a microfilm. Usually an image pattern on a form slide is focused by optics onto a microfilm in reduced dimensions. The prescribed resolution is not more than one pixel or dot on a microfilm, and this requires a positional accuracy of 10-60 .mu.m at the maximum in accordance with dimensional standards of form slides. Hence, a positional accuracy of about 5 .mu.m will usually suffice in practice. Stated another way, the accuracy of a form slide relative to the optical axis of the optics is required to be about 5 .mu.m.
Implementations for a shorter form selection time and a higher form positional accuracy heretofore proposed include a system using a rotatable disc or a hollow, polygonal rotatable frame having a plurality of side surfaces, with a plurality of form slides carried on the disc or the frame, as disclosed in Japanese Patent Application Nos. 46522/1982 and 46519/1982, both filed by the same assignee as the present application. In these systems, a plurality of form slide carrying devices are used for accurately fixing individual form slides in advance on the disc or the polygonal frame, taking into account the relation of the form slides with a predetermined projection position. The form slide carrying devices are controlled to move into register with an optical axis and stop thereat. These systems, unlike those with a stocker or a holder, insure a positional accuracy well feasible for practical use.
The present invention constitutes a further improvement over this type of prior art multi-form slide selectors.